Soil quality and nitrate percolation as affected by the horticultural and arable field conditions of organic and conventional agriculture

The effect of organic and conventional agriculture was studied on major soil-quality characteristics and on permanent nitrate loss in soil-crop-cultivation systems. The percolation of the nitrate content was assessed in the effluent water during two vegetative periods using belowground lysimeters in various crop rotations on a slightly humous sandy soil in Hungary. As well as annual element analysis and organic matter assessments, the bi-weekly nitrate-leaching tendency was monitored as a function of organic and conventional agriculture under horticultural and arable field conditions. A large annual variation in the nitrate content was detected in the percolated water during both vegetative periods at the 500-600 mm rainfall level. Residual nitrate content of the soils was higher in conventional treatments, while for the microelements an increasing amount was realized after three consecutive vegetative periods in the organic agriculture. A positive relationship was recorded between the nitrate loss and both rainfall pattern and fertilizer/pig manure application. In addition to these findings the horticultural practice could produce a higher rate of percolates and an increased cumulative nitrate loss in both crop years. Although the rates and the tendencies of the farmyard manure or fertilizer applications were rather dependent on the cultivated crops, a lower nitrate loss was found in the arable field conditions. In horticultural practice, however, permanently a more regular nitrate loss could be recorded, especially in the organic agriculture. Results showed that such regular monitoring with the applied lysimeter technique should serve as a reliable tool for managing economically- and environmentally-sound agricultural practices.